Study Of PLLA Nanofibrous Scaffolds And PLLA Microspheres

Firstly,PLLA nanofibrous tubular scaffolds were fabricated by a technology combined thermally induced phase separation and centrifugation with particle leaching,in this paper.Under centrifugal force,the scaffold formatted a tubular structure,and polymer occurred phase separation,at the same time.We studied the PLLA scaffolds nanofibrous structure affected on input voltage and phase separation temperature.Through SEM images,we found that like extra cellular matrix nanofibrous tubular scaffolds were generated by the method with 4.00V input voltage and-15? phase separation temperature.Meanwhile,we took scaffolds into cells culture in vitro.The culture results indicated that nanofibrous tubular scaffolds we created had excellent biocompatibility,and it's expected to be applied in bone repair and regeneration.Secondly,although PLLA has good biocompatibility,high hydrophobility could restrict PLLA to develop in tissue engineering.In order to improve the hydrophilicity of PLLA,we adopted ammonolysis technology to introduced hydrophilic amino into PLLA chains.In addition,we combined with thermally phase separation technology to fabricate a construction with nanofibers in PLLA scaffolds which were modified through ammonolysis.Change the nonsolvent composition of solvent system from water to an aqueous solution of NaOH/urea.The alkaline hydrolysis reacted in PLLA with NaOH,which the urea would participate in the reaction of ammonolysis at the same time.Using X-ray photoelectron spectroscopy(XPS)to detect the chemical energy of nitrogen that was included in amino.The results indicated that the solvent/nonsolvent(dioxane/NaOH-urea-water)ratio were 85/15 and 90/10(w/w),could detect the existence of Nls peak.Combined with SEM diagrams,we could found that when the solvent/nonsolvent was 90/10 could fabricated scaffolds with uniform nanofibrous network structure.Analysis the result of the scaffolds cells culture in vitro,the amino modified with nanofibrous network structure scaffolds had better biocompatibility.Finally,PLLA was not only widely applied in field of bone tissue engineering scaffolds,but also in study of protein drug release and cell carrier microspheres.And the study of cell carrier microspheres is significance for tissue engineering.This paper still used the thermally induced phase separation technology to fabricate PLLA microspheres.By adding hydrophilic fills to change the rich phase of system from hydrophobic polymer to hydrophilic fills,then phase separated under low temperature.We discussed the state of fills,solvent composition and polymer concentration which made the effect on PLLA microspheres morphology.SEM diagrams indicated that preparation of the surface of the microspheres with solid sucrose fills had fiber woven network structure.However,the surface of microspheres with glycerol fills was smooth,relatively.With concentration of polymer increased,the microspheres had rougher surface and bigger specific surface area.The change of nonsolvent composition leaded to the increase of hydrophilic groups which naked out the polymer chains,and microspheres with porous surface construction.In addition,compare with microspheres with relatively smooth surface,fiber network structure microspheres had better slow-release property.The scaffolds cell culture in vitro,the results showed that the microspheres fabricated by sodium hydroxide-urea-water and glycerin fills did not become cell carriers,and other three microspheres had a feasibility to become cell carriers.